1. Field of the Invention
The present invention relates generally to a mechanism for generating vibration and, in particular but not exclusively, to a vibration generating mechanism for generating vibration energy in the vertical direction by making use of repulsive forces of a plurality of permanent magnets.
2. Description of Related Art
An exciter or vibration generator has been used to artificially generate vibration to investigate vibration characteristics of a structure. Exciters of an electromotive type and those employing an unbalanced mass or a cam are known.
An exciter employing a link mechanism such as, for example, a crank is, however, required to have a relatively large drive motor because a load is directly applied to the drive motor, while an exciter of the electromotive type cannot cope with low frequencies.
Also, because conventional exciters are generally large-sized, not only a relatively large space but a time-consuming installation operation are required. Further, the conventional exciters generate a large amount of heat and, hence, require forced air cooling by a fan or the like, which in turn causes a problem in that noise evaluation cannot be achieved.
In addition, because the conventional exciters are generally of a complicated structure and are, hence, heavy and costly, light and inexpensive ones have been desired.